E/MJ : engineering and mining journal . few years ago into a piofitable one. The Herman vein consists of quartz, lying whollywithin schist walls. This schist is blocky and hasmany cross fractures. On the hanging wall thereis a layer of soft black slate, making the upper partheavy and subject to many falls without is especially true if a large surface is exposedto the air for any length of time. to four inches in diameter and sometimes twelveinches long. Some of them were clear quartz andsome stained from the iron in the vein, producingdifferent shades of amber and brown. Contrary
E/MJ : engineering and mining journal . few years ago into a piofitable one. The Herman vein consists of quartz, lying whollywithin schist walls. This schist is blocky and hasmany cross fractures. On the hanging wall thereis a layer of soft black slate, making the upper partheavy and subject to many falls without is especially true if a large surface is exposedto the air for any length of time. to four inches in diameter and sometimes twelveinches long. Some of them were clear quartz andsome stained from the iron in the vein, producingdifferent shades of amber and brown. Contrary to theusual rule, the gold content increased in or near thesewatercourses, so that often the mill would be stamp-ing rock crystal and recovering gold. Surroundingthe courses the vein was usually shattered; thequartz could be dug out by hand and resembled dirtyrock salt. The greatest gold value was found inthese places, and depth may prove that the pocketsresult from a mechanical sorting and concentrationof the gold from the vein FIG. 1. FIRST SYSTEM USED AT HERMAN MINE. OVERHAND .STOPING USING SQUARE SETS The quartz vein is from four to thirty feet gold is confined almost entirely to shoots, whichare generally in the thickest part of the vein. Usuallythe value decreases without any change in the thick-ness, although there is a physical change, which thetrained eye can detect, as the quartz becomes denserand more glassy as the value decreases. There aremany high-grade spots in the shoot, but as a wholethe ore is a low-grade, and all the methods of miningand milling were consequently governed by that cir-cumstance. The quartz in the principal oreshoot was unusuallyabrasive to tools and mill, but was brittle and easilybroken. It contained numerous water courses, someof which occurred at a depth of 1,000 ft. below theoutcrop and formed caverns or holes six or eightfeet in diameter. These caverns were lined withbeautiful quartz crystals from a fraction of an inch T
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Keywords: ., bo, bookcentury1900, bookdecade1910, booksubjectmineralindustries
